Attitude control means for aircraft



June 20, 1939. A, PRQTZEN 2,162,862

ATTITUDE CONTROL MEANS FOR AiRcRAFT Filed May 20, 1958 so 47 3| I- a2 Ahllimifl 49 32 umm 30 3| no 75 /'I Z I INVENTOR.

I00 I la T 1 M v ATTORNEY.

Patented June 20, 1939 p 2,162,862 ATTITUDE ooN'rRoL MEANS FOR AIRCRAFTArmand Protzen, Berlin-Spandau, Germany, as-

signor to Siemens Apparate und Maschinen Gesellschaft mit besehriinkterHaftung,'Berlin, Ger many Application May 20, 1938, Serial No. 209,117In Germany May 22, 1937 .8 Claims. (01. 244-77) This invention relatesto attitude control means for aircraft, and more particularly to meansfor controlling an aircraft following a curved flight .path.

ii One of theobjects of the present invention is to provide novel meansfor governing the atti-. tude of an aircraft in curved flight wherebythe craft will, assume the proper banking angles.

A further object of the invention is to provide novel means forgoverning the control surfaces of an aircraft whereby, for curvedflight, the ailerons are automatically actuated simultaneously with therudder; I

Another object is to provide novel means of .15 the above characterwherein a direction transmitter positions a rubber, and in associationtherewith, an artificial horizonpositions suitable ailerons.

A further object is. to provide novel means of the above characterwherein, during a curved flight, the ailerons of an aircraft areinitially adjusted by the combined action of a course control member andan artificial horizon, and are finally adjusted by the action of meanswhich are responsive to the relative position of the apparent verticaland the vertical axis of the aircraft. Another object is to providenovel, means for controlling the attitude of an aircraft in curvedflight, said means being governed by manually controlled means. I

An additional object is to provide novel means of the above characterwhereby the, vertical axis of an aircraft may be quickly andautomatically 9 brought into coincidence with the apparent verti- 1 calwhile banking in a curved flight path.

Another object is to provide novel means of the above character wherebythe skidding of an aircraft while. making a turn is reduced to aminimum.

. The'above and further objects and novel features will more fullyappear from the following detailed description when the same is read inconnection with the accompanying drawing. It

is to be expressly understood, however, that the 5 drawing is forpurposes of illustration only and not intended as a definition of thelimits of the invention, reference for this latterpurpose being had tothe appended claims.

In the drawing, wherein like reference char- 5 acters refer to likeparts throughout the several views,

Fig. 1 is a schematic diagram of one embodiment of the invention; I

Fig. 2 is a schematic diagram of a device for controlling the flow ofcurrent to a coil which may be employed in the present invention; and,

Fig. 3 is a' schematic diagram of an inclination transmitting devicewhich may be employed in the present invention. The form of theinvention illustrated, by way 1 of example, is a device for controllingthe attitude of an aircraft while following a curved flight path wherebythe vertical axis of the aircraft may bebrought into the proper angularrelation with the apparent vertical. The device 10 is constituted by acourse control member which may comprise a hand-controlled electricswitch which governs suitable means for positioning a course rudder andalso governs the current flowing to a rotary magnet which by suitableamplill fying means positions the ailerons of the aircraft. Anartificial horizon, for example, of the gyroscopic type, operativelyconnected to said rotary magnet by a second coil which is energizedwhentransverse inclinations occur, neutralizes the ac- 2o tion of the firstcoil and thecourse control member upon said rotary magnet,whereuponmeans which 1 are responsive to the relative angular positionof the apparent vertical and the vertical axis of the craft furtheradjust the ailerons to 25 bring said craft into the proper bankingangle.

In the form shown in Fig. 1, novel means are provided for governing theapparatus comprising a switch member l0 having, for example, a hand knobIlla. Switch I0 is operatively connected to 30 a servo -motor II which,by adjusting a gyro compass I2 positions by suitable means (not shown)associated therewith a course rudder I3. Switch I0 controls both thedirection and speed of rotation of motor H and further is connected to a35 stator coil M of a rotary magnet l5 by means of leads l6, Mia and[6b, the latter lead being connected through an energy source I wherebysaid switch, depending upon the direction in which it is moved from acentralized position,. controls the direction of the field of said coil,the field being of constant strength. For a purpose to later appear, asolenoid IT by means of leads I8a, Illa is alsoconnected to'switch Illand is energized upon a movement of the switch from 45 the centralposition. Rotary magnet l5 .com-

, prises a control element for a servo-motor, said magnet beingconstituted by a conventional stator l9 and armature I911, the latterbeing at-. tached to an arm 20 which is operatively con-..

nected,"by means of a rod 20a, to a servo-motor" 2| which positionsalierons 22, 22. Arm 20 is normally held in a centralized position bymeans of opposed springs 20', '20. I

, In cooperation with the switch member I con- ,5;

trolling coil H which has a constant field strength independent of thedisplacement ofknob Illa, two additional members influence coils uponthe rotary magnet, and hence the ailerons, said members comprising anartificial gyroscopic horizon 23 and a banking acceleration indicator24, to

be later explained, which respectively control the current to a pair ofcoils 25 and 28 upon said stator. The former member is constituted by agyro rotor (not shown) having a shaft 21 which is mounted in a housing28 having trunnions 29, 23 which are supported in a conventional gimbalring 38 having trunnions'3i, 3| resting in bearings 32, 32. The axis oftrunnions 29, 23 is parallel to the longitudinal axis of the craft asindicated by arrow 33 when the gyroscopic pla e of rotation is in thehorizontal. Also parallel to said longitudinal axis are the shaftportions'34a, 34a of a crank 34 which is operatively connected to gyrohousing 28 by means of .an upwardly extending member 35 upon the topthereof, having lingers 35a, 35a between whichthe crank 34' is slidablyheld whereby any angular displacement of the housing 28 about trunnions.29; 29,1. e., transverse displacement, is transmitted to said crank andto a current control device for coil 25. The current control devicecomprises aconventional bolometer 36 having a nozzle portion 31 anddouble coils or resistance 38, 38in bridge connection by means of leads39, 48, 4| with coil 25, the latter lead being connected to said coilthrough a suitable energy source 42. ;The field strength of coil 25 isselectedto equal that of coil l4 when said bridge connection isunbalanced. The air jet from nozzle portion 31 is normally preventedfrom reaching either of the coils 38, 38 by means of a plate ordiaphragm 43 which is interposed therebetween and positioned by thegyroscopic horizon, being operatively connected to shaft 34a and adaptedfor angular displace-- ment therewith. 1

Suitable means which, for a reason to later appear, are effective onlywhen switch i8 is centralized, are provided for controlling'transverseinclinations of the craft in association with horizon 23. The means areconstituted by a pendulum 44 pivotally mounted upon a shaft 44a which isaxial y parallel to shafts 34a, 34a and trunnions 29, 29. Pendulum-44moves between two ctric contacts 45, 46 which are connected to oppositeextremities of a coil 41 by leads 48, 49. The center of said coil, by alead 58, is connected to said pendulum through contacts 580 and 58b of aswitch to be later described and through an energy source Coil 41 isplaced adjacent a permanent magnet 52 which is rigidly attached toone'of the trunnions 3|, 31 whereby a turning moment is produced uponsaid magnet parallel to the longitudinal axis of the craft.v Pendulum 53is normally held in a centralized position byopposed springs 54, 54 andispro- "of said bolometer and thus normally is interposed between an airnozzle 88 and a pair of double resistances or coils 8|; 8| which byleads 82, 83 and 84 are in conventional bridge connection with coil 28.Lead 84 is connected through an energy source 85 to said coil.

Inorder that the banking acceleration indicator may be of highsensitiveness, the gear ratio between sector 55 and spur gear 58 shouldbe high. The springs 54, 54 which normally centralize the pendulumshould be in high tension whereby a high natural frequency'of thependulum is obtained, thus increasing the accuracy of the apparatus.

In order to avoid the eflect upon the apparatus of disturbingprecessional movements of the gyroscopic horizon while the aircraft isin curved flight, a switch 66 is provided for disconnecting pendulum 44,said switch having a rod 81 attached thereto which extends into thesolenoid II. The switch 88-normally engages the above-mentioned contacts58a and 50b in the circuit of pendulum 44, being held thereagainst by aspring 88. A second pair of contacts 840 and 84b in lead 64 is providedadjacent thereto, the latter two contacts being interconnected by switch88 when solenoid I1 is energized and rod 81 withdrawn against thepressure of spring 88.

In operation, if it is desired to make a change of course the hand knobIlla of switch I8 is angularly displaced to the right or left from thecentral position, as the case may be, by an amount corresponding to thespeed at which it is desired to move rudder l3. Several reactions occursimultaneously when this displacement is made, namely, motor |I rotatesto move rudder l3, coil I4 exerts a turning moment upon the armature leaof the rotary magnet, thus deflecting the ailerons, solenoid I! isenergized withdrawing switch 88 from its normal positionagainst contacts58a and 50b to a second position connecting contacts 84a and 84b. Thedeflection of the rudder and the ailerons from their normal centralpositions will, in turn, produce simultaneously a turn about thevertical and longitudinal aircraft axes. The resulting transverseinclination of the craft in the curved flight path willcause air nozzle31 to be displaced relative to diaphragm 43, the latter being held inthe true vertical by artificial horizon 23. An air Jet from'said nozzlewill be directed upon one of the coils 38, 38 altering the resistancethereof and unbalancing the bridge circuit, of which it is a part, thusunbalancing the field of coil 25 and causing the same to neutralize themotor action of coil l4 upon armature |9a whereby the arm 20 returns toits initial central position. From this point on, while switch i8 isdisplaced, the banking accelerator indicator influences the initiallycompleted when switch 88 engaged contacts 84a and 64b as abovementioned. The banking indicator will not be deflected from its centralposition so long as the vertical aircraft axis and the apparent verticalare, in the proper angular relation, i. e., in most aircraft, incoincidence. This is because the centrifugal forces acting, when saidproper angular relation exists, will maintain the pendulum 53 in thecentral position. However, if the vertical aircraft axis moves away fromthe apparent vertical when in curved flight, due, for example, toinsufllcient transverse inclination as produced by aileron displacement,a skidding in the turn will occur which will permit centrifugal force todeflect said pendulum. This "skidding is referred to as a bankingacceleration and always occurs when improper transverse inclinationexists. The deflection of the pendulum against the pressure of springs54, 54 will displace diaphragm 58 of bolometer 51 and in a manner.analogous to that of bolometer 38 unbalance the field of coil 28 by anamount which is a function of the angular discrepancy between theapparent vertical and the vertical aircraft axis. Consequently, thefield strength of coil 28 will be a similar function and armature iSa ofrotary magnet IE will be accordingly displaced to-further deflectailerons 22 to bring the craft to the proper transverse inclinationwhereby the vertical aircraft axis and the apparent vertical are broughtinto coincidence. When the desired course change has been made the knob"a is returned to its initial position, coil i4, solenoid l1, and motorI i are deenergized. The switch 85 is moved by draw spring 88 intoengagement with contacts 50a, 50b, thus complet- -ing the operativeconnection of pendulum 44 to the artificial horizon. The ailerons nowwill be readjusted'by the gyroscopic horizon to reduce -the transverseinclination tozero and restore the craft to a horizontal position in amanner known per se.

In accordance with the explanation made above, the initial excitationofthe rotary magnet is caused bym'eans of a coil I4 on the stator ofsaid magnet. It is not necessary, however, that this initial excitationbe effected by a coil in this manner; for example, coil i4 may beeliminated and the same-result obtained by connect ng an addedresistance to either of the coils 38, 38 when knob iOa is turned fromthe central position. One form of this construction is illustrated inFig. 2 wherein a bolometer 36 is employed similar to that of Fig. 1 withthe exception that an added resistance AC is connected between coils 38,38. An arm 69 mounted upon shaft 10 is positioned either at a centralpoint B on said resistance or at either extremity thereof, dependingupon whether switch member i is in a central position or displaced tothe right or left. Shaft 18 is operatively connected to switch memberill, for example, by a relay ll having leads 13,14 and 15, the latterhaving an energy source 18 therein.

The operation of this embodiment is similar to that shown in Fig. 1,with the exception that the motor action of rotary magnet i is initiallyproduced by coil 25 in the following manner, When flying upon a straightcourse, the knob iiia and arm 88 are in centralpositions, equal currentsflow in the coils 38, 38, and the bridge circuit is balanced. However,if the course control knob lfla is moved, for example, to the right thearm 69 will be deflected from its central position to point C and thebridge circuit will be unbalanced causing coil to exert a turning momentupon armature i8a which will, by means of servo-motor 2i, deflectailerons 22. The craft will therefore be transversely inclined wherebynozzle 31 will move relative to diaphragm 43 to direct an air jet uponthe coil 38 which is adjacent to point A of resistance AC. 1 Theresistance AC is selected such that when thediaphragm 43is displacedunder these conditions the air jet reduces the resistance of the exposedcoil 38 to the point where equal currents flow on both sides of thebridge, thus balancing the bridge and reducingthe motor action of coil25 to zero. The ailerons will be further positioned by the bankingacceleration indicator 24 in the manner above described. When thedesired course change has been made knob iila is recentralized, arm 68moves to central point B on resistance AC, the bridge circuit ofbolometer 38 is-unbalanced, coil 28 is disconnected and col! 25 exerts aturning moment upon the armature to recentralize the ailerons and reducethe transverse inclination to zero. The diaphragm 43 is again interposedbetween the air jets of nozzle 31 and the coils 38, 38 and the bridgeconnection is rebalanced. The craft is thus restored to its originalattitude upon a different course.

The banking acceleration indicator 24 employed in Fig. 1 which isresponsive to angular differences between the aircrafts vertical axisand the apparent vertical, may be replaced by any other type of bankingindicator, for example, by a pendulum or by a device which determinesthe angle between the true and apparent verticals'by the product of theangular velocity of the aircraft about its vertical axis and the airspeed. Since the angular velocity of the aircraft about its verticalaxis is proportional to the velocity by which the adjustment of thebase, that is, the control zero position of the gyro compass is effectedby I the motor .i i, it is determined in a most simple 19, 19. Theformer impulse may be obtained from the field of said motor and thelatter from a suitable air speed indicator controlling an electriccurrent. A shaft 88 extending from the multiplying mechanism positionsan arm 8i attached thereto. Arm 8i is provided at the extremitiesthereof with a bifurcated portion having fingers 82, 82' at right anglesto the arm. Between said fingers and normally centered in spacedrelation therebetween is a rod 83 pivotally mounted upon a shaft 84coaxial with shaft 80. Rod 83 is opera-tively connected to theartificial horizon 23, whereby it is normally held in the true vertical,by means of an arm 85 which is pivotally connected to the rod at 83a andwith diaphragm 43, of said horizon, at 430. The fingers 82, 82' and therod 83 are connected to coil 26 of rotary magnet i5 by leads 62, 83, 64,respectively, in a manner similar to that in which the coils Si, iii areconnected to coil 26 in Fig. 1,

In the operation of this banking indicator the 'arm 8i is positioned bythe air speed, the angular velocity of motor II, and by the aircraftitself since the multiplier is mounted on the craft. So long as thevertical axis of the craft coincides with the apparent vertical when ina curved flight, the arm 83 will be in the true vertical, the rod 83 iscentered between fingers 82, 82', and no current flows to coil 26 toinfluence the ailerons 2i. However, if the verticalaxis of the craftmoves away from the apparent vertical, the arm 8i will be deflected fromthe true vertical in response thereto, and rod 83 will contact eitherfinger 82 or 82 as'the case may be, thus energizing coil 26 to movearmature i9a and thus to deflect ailerons 22 to compensate for theangular discrepancy between said apparent vertical and the aircraft'svertical axis, The operation of the remainder of the apparatus issimilar to that described for Fig. 1.

There is thus provided a novel attitude control apparatus whichaccurately controls the transverse inclination of an aircraft while incurved flight whereby the crafts vertical axis is held in. a properangular relation to the apparent vertical,

thus preventing skidding while in curved flight. The apparatus quicklycauses the craft to assume the proper attitude by simultaneouslydeflecting the course control rudder and the ailerons.

, Although only three embodiments of the present invention have beenillustrated and described in detail, it is to be expressely understoodthat the vention, reference will be had primarily to the.

appended claims.

,What is claimed is:

1. In apparatus of the class described, an artificial horizon, a controlsurface for governing the course of a vehicle, control surfaces forgoverning the transverse inclination of said vehicle, power means formoving the first-named surface, power means for actuating thesecondnamed surfaces, and means for simultaneously actuating said powermeans, without influencing said horizon. I

2. In an attitude control apparatus for aircraft, a course controlsurface having power means operatively connected thereto, aileronshaving power means operatively connected thereto, a control element forsaid last-named power means, speed control means for said first-namedpower means, means for displacing said control element simultaneouslywith the actuation of said speed control means, means for returning saidcontrol element in response to a predetermined transverse inclination,and means for further displacing said control element in response toangular deviations of the apparent vertical and the vertical axis ofsaid aircraft.

3. In an attitude control apparatus for aircraft, a course controlsurface, power means therefor, transverse inclination control surfaces,power means therefor, a control element for said last-named power means,speed control means for said first-named power means, means for exertinga force of constant magnitude upon said control element, said last-namedmeans being effective when said course control surface power means areenergized, means effective on reaching a predetermined transverseinclination for counteracting the effect of said force upon said controlelement, and means responsive to angular discrepancies between anapparent vertical and a vertical axis of said aircraft for moving saidcontrol element.

4. In an attitude control device for aircraft, a course control surface,power means therefor, transverse inclination control surfaces, powermeans therefor, a control element for said last-' named power means,speed control means for said first-named power means, means for exertinga force of constant magnitude upon said control element, an artificialhorizon having trans verse inclination control means associatedtherewith, a banking acceleration indicator, said artificial horizonbeing operatively connected to said control element, and means forrendering ineffective said transverse inclination control means and foroperatively connecting said indicator to said element, said means beingeffective when said course control surface power means are energized.

5; The combination with a course rudder and transverse inclinationcontrol surfaces for an aircraft of means for determining a truevertical, means for determining the deviation of a vertical axis of saidaircraft from an apparent vertical, said means being effective when incurved flight, power means for said course rudder, power means for saidtransverse inclination control surfaces, a control element for saidlast-named power means, means for producing a controlled impulse to saidcontrol element, means for producing an impulse in response to adeviation of said vertical axis from said true vertical, means forproducing an impulse in response to a deviation of said vertical axisfrom said apparent vertical. said impulses acting upon said controlelement whereby said element is actuated in response to the sum of saidimpulses, and means including said controlled impulse means forenergizing said course rudder power means when said first-named impulseis acting.

6. The combination with a course rudder and transverse inclinationcontrol surfaces for an aircraft of means for determining a truevertical, means controlled by movement of the craft and responsive tothe angular velocity of said craft about the vertical axis thereof andto the air speed thereof for determining the angular relation of theapparent and true verticals. said last-. named means establishing a truevertical when a vertical axis of said craft coincides with said apparentvertical, meansfor comparing indications of said first-named andsecond-named means, and means for governing said transverse inclinationcontrol surfaces in accordance with the difference between the comparedindications.

7. In an attitude control device for aircraft, a course control surface,transverse inclination control surfaces, power means for said coursecontrol and transverse inclination surfaces, an artificial horizonhaving transverse inclination control means associated therewith, abanking acceleration indicator, a control element for said transverseinclination power means, and means for rendering ineffective saidtransverse inclination control means and for operatively connecting saidindicator to said element, said means ,being effective when saidcoursecontrol surface power means are energized.

8. In an attitude control apparatus for aircraft, a course controlsurface, transverse inclination control surfaces, power means for saidsurfaces, and a control element for said power means comprising anelectrical circuit including variable resistance, means for varying saidresistance in proportion to the transverse inclination of said craft forcontrolling said transverse inclination power means, and manuallyoperated means for varying said resistance whereby said course powermeans are controlled.

ARMAND PROTZEN.

